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Message-Id: <20190708174913.123308-5-thgarnie@chromium.org>
Date: Mon, 8 Jul 2019 10:48:57 -0700
From: Thomas Garnier <thgarnie@...omium.org>
To: kernel-hardening@...ts.openwall.com
Cc: kristen@...ux.intel.com,
keescook@...omium.org,
Thomas Garnier <thgarnie@...omium.org>,
Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
"H. Peter Anvin" <hpa@...or.com>,
x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v8 04/11] x86/entry/64: Adapt assembly for PIE support
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.
Position Independent Executable (PIE) support will allow to extend the
KASLR randomization range below 0xffffffff80000000.
Signed-off-by: Thomas Garnier <thgarnie@...omium.org>
Reviewed-by: Kees Cook <keescook@...omium.org>
---
arch/x86/entry/entry_64.S | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 0ea4831a72a4..9f55a359c896 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1309,7 +1309,8 @@ ENTRY(error_entry)
movl %ecx, %eax /* zero extend */
cmpq %rax, RIP+8(%rsp)
je .Lbstep_iret
- cmpq $.Lgs_change, RIP+8(%rsp)
+ leaq .Lgs_change(%rip), %rcx
+ cmpq %rcx, RIP+8(%rsp)
jne .Lerror_entry_done
/*
@@ -1506,10 +1507,10 @@ ENTRY(nmi)
* resume the outer NMI.
*/
- movq $repeat_nmi, %rdx
+ leaq repeat_nmi(%rip), %rdx
cmpq 8(%rsp), %rdx
ja 1f
- movq $end_repeat_nmi, %rdx
+ leaq end_repeat_nmi(%rip), %rdx
cmpq 8(%rsp), %rdx
ja nested_nmi_out
1:
@@ -1563,7 +1564,8 @@ nested_nmi:
pushq %rdx
pushfq
pushq $__KERNEL_CS
- pushq $repeat_nmi
+ leaq repeat_nmi(%rip), %rdx
+ pushq %rdx
/* Put stack back */
addq $(6*8), %rsp
@@ -1602,7 +1604,11 @@ first_nmi:
addq $8, (%rsp) /* Fix up RSP */
pushfq /* RFLAGS */
pushq $__KERNEL_CS /* CS */
- pushq $1f /* RIP */
+ pushq $0 /* Future return address */
+ pushq %rax /* Save RAX */
+ leaq 1f(%rip), %rax /* RIP */
+ movq %rax, 8(%rsp) /* Put 1f on return address */
+ popq %rax /* Restore RAX */
iretq /* continues at repeat_nmi below */
UNWIND_HINT_IRET_REGS
1:
--
2.22.0.410.gd8fdbe21b5-goog
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